油区构造解析课件-9底辟构造：Diapirs+structure

第八节垂直构造

底辟构造

Diapirsstructure

地下较深处的密度相对小的高塑性岩层或岩体在差异重力等机制作用下向上拱起或刺穿上覆岩层形成的一种构造。是垂直构造类型的一种。

一、底辟构造结构要素及基本特征：

（1）.底辟核

（2）.核上构造

（3）.核下构造

第八节垂直构造

底辟构造

Diapirsstruc1－底辟核；2－核上构造；3－核下构造1.底辟构造的结构要素1－底辟核；2－核上构造；3－核下构造1.底辟构造的结构要小型底劈构造小型底劈构造小型底劈构造小型底劈构造盆地中的底劈构造？？盆地中的底劈构造？？泥底劈盐底劈（硫酸盐、碳酸盐、石盐）岩浆底劈2.底劈构造核部岩性类型泥底劈盐底劈（硫酸盐、碳酸盐、石盐）岩浆底劈2.底劈构造核部盐底劈盐底劈TopTagluStructuremapshowingtherelationshipbetweenthepresent-daycompressional泥底劈ReleasingBend释放弯曲ReatrainningBend约束弯曲TopTagluStructuremapshowin3.底劈构造核上部的正断层常呈环状或放射状3.底劈构造核上部的正断层常呈环状或放射状乐东气田——乐东l5-1构造是莺歌海盆地诸多泥底辟构造之一乐东气田——乐东l5-1构造是莺歌海盆地诸多泥底辟构造之一油区构造解析课件--9底辟构造：Diapirs+structure油区构造解析课件--9底辟构造：Diapirs+structure油区构造解析课件--9底辟构造：Diapirs+structure油区构造解析课件--9底辟构造：Diapirs+structure油区构造解析课件--9底辟构造：Diapirs+structure油区构造解析课件--9底辟构造：Diapirs+structure油区构造解析课件--9底辟构造：Diapirs+structure油区构造解析课件--9底辟构造：Diapirs+structure放射状平形状放射状平形状盐构造可以由以下6种机制触发引起：①浮力作用;②差异负载作用;③重力扩张作用;④热对流作用;⑤挤压作用;⑥伸展作用。核部由盐类组成的底劈构造称为盐丘。4.盐丘的形成机制盐构造可以由以下6种机制触发引起：核部由盐类组成的底劈构造称撒哈拉穹窿——理查德构造撒哈拉穹窿——理查德构造油区构造解析课件--9底辟构造：Diapirs+structure理查德构造——相当于非洲之眼的眼球理查德构造——相当于非洲之眼的眼球非洲之眼是晚白垩纪碱性岩浆热液上侵，沿灰质白云岩陆架的环状同生断裂上侵，引发地表穹隆侵蚀和热液卡斯特作用，由此而形成一个直径40公里的眼珠状构造。岩浆上侵穹窿？非洲之眼是晚白垩纪碱性岩浆热液上侵，沿灰质白云岩陆架的环状同含岩盐盆地的盐丘是是最常见的一类底劈构造，与油气关系密切。世界含盐盆地分布含岩盐盆地的盐丘是是最常见的一类底劈构造，与油气关系密切。世盐丘的几种剖面形态盐丘的几种剖面形态盐丘的几种剖面形态盐丘的几种剖面形态构造位置与盐构造类型构造位置与盐构造类型Asillustratedonthisseismicline,itisquiteobviousthesaltandoverburdenhavebeenshortened(compressionstillisgoingon)byacompressionaltectonicregimethatsomeassociatewithridgepushingforces.Thefaultsinthetopoftheantiformsarestrike-slipandnotnormalfaults.Timeslicesbetween3.0and3.2seconds,stronglysuggestthatsuchafaultselongatetheanticlineaxisalongthes2

二、盐底劈构造类型及特征盐背斜1.挤压盐构造AsillustratedonthisseismicFig.25-Thesaltweldinthecentralpartofthelinesuggeststhatbeforedeformationthesaltlayerwascontinuousbetweentheyellowandbrowninterval.Then,theinfra-saltstratawerelengthenedbynormal-faultscreatingpotentialvoidsthatwerefilledbysalt(“saltgrabens”)duetoalateralsaltflowage,whichcreatedawindowinthesaltlayer.Finally,acompressionaltectonicregimeshortenedthecoverinvertingthesaltgrabens.Fig.25-ThesaltweldintheItisinterestingtonoticethatindepth,thedistalthrustfaultcorrespondstotheseawardlimitofasaltbasin.Seaward,thesaltisallochthonousandformsasaltnappe,whichhasbeenreactivatedandshortenedprobablybyridgepushforces.Itisquiteobviousthatthethicknessofthesaltisapparentandduetothrusting.Somearguedthatthesaltbeingthickerintheultradeepoffshorewastheproofofanuniquepristinesaltbasinthatwaslatersplitintwo.Recently,suchaerroneouslyhypothesishasbeensystematicallyfalsified.推覆体

外来盐ItisinterestingtonoticethTheregionalgeologicalsettingofthislinestronglysuggeststhesesaltstructureswerecreatedbyacompressionaltectonicregime.Themappingofthefaultsonthetopoftheoverburdenstructuresshowsthattheyaresmallstrike-slipfaultswhichelongatetheaxisoftheanticlinealongthe2.

TheregionalgeologicalsettinRidgepushforcesseemtoberesponsibleoftheshorteningofthecoverindeepwater,wheresaltdiapirshavebeensqueezedandbackthrusted,aswellasthe

mini-basinsbetweenthem.Thegeometricalrelationshipsbetweentheseismicreflectors(seismicsurfaces)andthemorphologyoftheseafloorstronglysuggestthatshorteningstillisgoingon.挤入底劈Ridgepushforcesseemtober该测线上，有微型盆地在外来岩层上，只能用原生盐抽真空作用来解释。在测线的中部，沿着陡冲断层，盐向上移动。右下角可见盐下地层和裂缝型盆地）盐排出盆地该测线上，有微型盆地在外来岩层上，只能用原生盐抽真空作用来解ThisinterpretationtakesintoaccounttheRayleigh-Taylorinstability.Duringlongtime,inthisarea,erroneouslylargediapiricstructures(>30kmwide)wereproposed.Withsuchlargesaltstructuresexplorationistsgiveuptheareaduetoabsenceofsignificanttraps(indepth,suchstructureswere3-4timesthickerthanthebasinitself).Itisobviousthatinterpretationswithsaltcanopystructuresstronglychangethepetroleumpotential,atleastthetrappingparameter.盐盖

SaltWeld-盐连接；盐颈ThisinterpretationtakesintoThe

primarysaltweldrecognizedinthecentralpartofthethelineemphasizesthetectonicdisharmonyassociatedwiththebottomofthesaltlayer.Theoverburdenandsub-saltstratashowquitedifferentdeformations.Saltrollerarerecognizedonthebottomofpre-raftstructures.

(原生的盐焊接被公认为在线的中部，强调构造不整合与盐层底部有关。盖层和盐下地层表现出不同的突变，岩盐隆起被认为在预流体结构的底部）盐滑脱

TheprimarysaltweldrecognizFig.12-Thisseismicline,fromtheNeuquenbasin(onshoreArgentine),illustratesacompressivestrike-slipshorteningoftheforedeepsediments,inwhichaCretaceousevaporiticlayer(Hutrimformation)wasdeformedinconcordancewithallotherintervals.Similarly,butnosoevident,anOxfordiansaltlayer(Auquilcoformation)wasinverted(invertedrift-typebasininlowermiddlepartoftheline)withdevelopmentof

“enechelonfolds”intheup-thrownfaultedblock.Notice,thattwodifferentcompressionaltectonicregimes,onewiththebasementinvolvedandayoungerwithoutinvolvementofthebasementcanalsoexplainedthedeformationrecognizedonthisline.压扭性盐构造Fig.12-Thisseismicline,frFig.13-Compressivestrike-slipstructures(faultedconical-folds)inducedbyreactivationoffracturezonesarefrequentinSouthAtlanticmargins.Loemesalt(KwanzaandSouthCongobasins)formsoftenthecoreofanticlinestructures.Similarly,theOligoceneunconformityisupliftedandlocallyerodedbeforebeingfossilisedbyTertiarydeepwaterdeposits.压扭性盐构造Fig.13-Compressivestrike-slInspiteofthestretchedhorizontalscale,thesaltflats,atthebottomoftheallochthonoussaltsheet,arequitewellrecognizedonthisline.

断坪

外来盐2.伸展盐构造InspiteofthestretchedhoriStretchingfaultsstrikeinalldirections.Theyareinducedbylocalextensiontectonicregimes,inwhich2and

3areequal.Astheyelongatethesedimentstoaccommodatethemtonewvolumeconditions,Onseismiclinestheyhaveoppositevergences.Theoretically,thesumofthrowswithoppositevergencemustbezero.伸展断层StretchingfaultsstrikeinalOnthisseismicline,adeep

primarysaltweld(around6seconds)underlinestheevacuationofautochthonoussalt.Intheupperstratigraphiclevels,allochthonoussaltisquiteobvious.Takingintoaccountthedimensionsofthecentralsaltbodyaswellasthegeometryoftheupperandlowercontacts,itcanbeconsideredasasaltlaccolith.盐盖

Onthisseismicline,adeeppSeismicexpressionoftheSigsbeeEscarpment.Themaindrivingmechanismofsuchbathymetricfeaturesiswellillustratedonthisprofile.SeismicexpressionoftheSigsInoffshoreBrazil,fromwherethislinecomes,thesourcesaltlayer,i.e.,autochthonoussaltoverliesthepotentialsourcerocks.ContrariwisetoWestAfricansaltbasins,wherethemajormarinesourcerocksisintheoverburden,here,thepotentialmarinesourcerocksneverreachedmaturation.Indeed,asillustrated,theoverburdenisrelativelythin.Itsmaximumthicknessisaround3seconds.

InoffshoreBrazil,fromwhereSalttonguesastheoneillustratedonthisseismiclinearequitedifficulttodistinguishofsaltlaccoliths

orsaltsheets

盐舌

盐斜坡SalttonguesastheoneillustAsillustratedonthisseismicline,thelateralflowage

ofthesaltisthemainresponsibleforthecreationofspaceavailableforthesediments,thatistosay,itinducesacompensatorysubsidence.Indeed,inthelowerintervalsoftheoverburden,thethicknessvariations(thinabovethebulgeandthickabovethesaltsynforms)canonlybeexplainbysaltflowage,inspiteofthefact,thatthegeometryoftheupperintervalsoftheoverburdensuggestsalateshortening.侧向流动

AsillustratedonthisseismicSaltrollersarecharacteristicofpre-raftdomain,whichgenerallyareassumedtobelocatedinupperslopeorplatform.ThislinecomesfromthedeepwaterofAngola,wheresaltrollersarequiteobvious.Suchanoccurrencehasimportantimplicationsfortheoriginofthehighqualitycalcareousreservoirs.盐隆起SaltrollersarecharacteristiThissaltsheetstillisconnectedwiththe

mothersourcelayer,whichispartiallyrepresentbyprimarysaltwelds.Thefeederortheramp,whichlaterwillbecomeacounter-regionalfault,iswellrecognized.Noticenthetopofthesaltsheet

several

Rohofaults.盐片

ThissaltsheetstillisconneAtthebottomofthissaltsill(i)basalcutoffs,(ii)saltflatand(iii)saltrampsareeasilyrecognized.However,thesesaltrampsshouldnotbeconfusedwiththesaltrampssynonymoffeeders.盐床AtthebottomofthissaltsilThesynkinematiclayers,asthoseillustratedabove,thickeningtowardthegrowth-faults.Theyrecordsedimentationduringsaltfloworduringanyothertypeofdeformation.Thelightgreenandblueintervalsareprekinematic,whichareroughlyisopach.同运动层Thesynkinematiclayers,asthFig.24-Thelengtheningofthesedimentsisevident.Thetectonicregimeischaracterizedby1vertical.Theantiformmorphologyoftheseabottomisquitesignificant.Themajorityofthenormal-faultsdieonthetectonicdisharmonyassociatedwiththesaltlayer(topofthesalt)

Fig.24-ThelengtheningofthFig.26-SaltridgesandgrowthfaultsarefrequentinSantosbasin(offshoreBrazil).Takingintoaccountthatthedeformationoftheinfra-saltstrataisapparentandduetovelocity-inducedlateralpull-ups,onecansaythatbelowthetectonicdisharmonythesedimentsarealmostundeformed.Aboveit,saltridgesandgrowthfaultsextendedtheoverburden.Fig.26-SaltridgesandgrowtFig.27-IndeepwaterAngola,CretaceoussedimentsandparticularlythePindaformation,whichisapotentialreservoirintervalintheoffshoreshelf,wereextendedbygrowth-faultsdevelopedonthetopofthesaltlayerduetoanextensionaltectonicregimecharacterizedby1vertical,2horizontalstrikingmoreorlesN-Sand3horizontalandW-E.Fig.27-IndeepwaterAngola,Thesaltpillowiscompletelydisconnectedofthemothersourcelayer.Itislimitedbytwo

primarysaltwelds.Thisantiformsaltstructure,recognizedin1968,onSeffellines,became,recently,wellknownofallexplorationistsworkinginWestAfricaoffshores.Indeed,majoroilfieldshavebeenfoundaroundthetopoftheantiform.Noticetheslightpull-upofthetectonicdisharmonyinducedbythesaltpillow.盐枕

3.差异压实盐构造ThesaltpillowiscompletelyFig.18-InNordkapbasin(BarentsSea),thebasementisnotinvolvedindeformation(atleastintheareawherethislinewasshot).Inabsenceofsignificanttectonicstress,thethickPermiansaltlayerflowedupwardformingquitelargesaltdiapirs,whichdeformedtheoverburden.Notethattheflanksofthediapiricstructuresarenotvertical(physicalimpossibility)andtheoverburdenismainlyprekinematic(regionally,theoverburdenshowsanorthwardthickening).Fig.18-InNordkapbasin(BareFig.20-Halokinesisisnotasimpleupwardflowageofthesubstratum.Indeed,averticalsediment/saltinterfaceisphysicalinstability.Asillustrated,onthisseismicline,aboveagivenpoint(inversionpoint),thedensityofthesaltishigherthanthedensityofthejuxtaposedsediments(seelater).Therefore,abovetheinversionpoint,saltflowslaterally.Indeed,thesedimentconfiningpressureisnotbigenoughtobalancetheconfiningpressureinducedbysalt.盐构造作用Fig.20-HalokinesisisnotaOnthisline,thesaltweldisquiteobvious.The

saltmotherlayerisrecognizedinbothsidesofthe

saltweld.Thedepocenterlocatedabovethesaltweldcanonlybeexplainedbycompensatorysubsidence,thatistosay,bywithdrawalofthesalt.Onthisline,thesaltweldisSaltweltsarenotsynonymofsaltanticlines.Theyareextensionalsaltstructures,generally,createdbysaltflowage.Sometimestheycorrespondtosaltupwellings,asillustratedonthisline.Theinternalconfigurationofthelowermostintervaloftheoverburdenisdivergenttowardthesynforms,whatsuggeststhatitisasynkinematiclayer.Thesaltstartedtoflowatquiteshallowdepth.SaltweltsarenotsynonymofThegeometricalrelationshipsbetweentheoverburdenreflectorsandthetopofthesalt,aswellasthethicknesschangesaremainlyinducedbysaltwithdrawal,whatcreatesasignificantdifferentialcompensatorysubsidence.Thegeometry,andtheinternalconfiguration,ofthelightgreenseismicinterval(outcroppingjustabovethesaltstructure)indicatesthatthesaltdiapirwasreactivatednotlongtimeago.ThegeometricalrelationshipsSecondaryperipheralsinksareoftenassociatedwithtectonicinversionswhetherduetoareactivationofthediapirorlateregionalcompression.SecondaryperipheralsinksareOnthisseismicline,theoverburdenisquitedeformed,whilethesub-saltstrataismainlyundeformed.Theundulationsofthesub-saltstrataareapparent.Theyareinducedbylateralchangesinthevelocityoftheoverburden.Indeed,attheverticalofeachsaltdome,thesub-saltstrataarepulled-up.Themajorityofthesaltdomesisdisconnectedofthe

mothersourcelayer.Infact,theyareseparatedby

primarysaltwelds

盐帽Onthisseismicline,theoverAsillustratedabove,onecansaysaltplugsarecomposedbyastemandabulb.Onthisline,thesaltstockisdisconnectedfromthemothersourcelayer.Twoprimarysaltweldsseparatethesaltstockfromthemothersaltlayer.盐株Asillustratedabove,onecanOnthisseismicline,thestemisrelativelynarrow,incircumference,inproportiontotheheightofthediapir,whichseemscompletelydisconnectedofthemothersourcelayer.Indeed,twoprimarysaltweldscanberecognizedaroundthediapir.茎Onthisseismicline,thestemSaltstocksareformedbyastemandabulb.Theycanbeconnectedordisconnectedofthe

mothersourcelayer.盐干球茎柱茎SaltstocksareformedbyastThelateralsaltflowageorsaltreduction,i.e,theevacuationofthesaltcreateda

primarysaltweldandalocaldepocentersintheoverburden.Thesaltreductionstronglyincreasedthespaceavailableforthesediments(accommodation),whichgeneratedthreelocalbutanobviousdepocentersinthesynkinematicintervalsoftheoverburden.Thelightblueintervalseemsprekinematic.

盐消减

ThelateralsaltflowageorsaThesuturesbetweenthedifferentsaltstockstoformasalt-stockcanopystillareeasyrecognizedonthistimeslice,whichdepthislessthan0.5secondbelowseafloor.盐株顶盖

ThesuturesbetweenthedifferAllochthonoussaltsheetsorsaltstockscangatheredtoformlarge

saltnapesorsalt-stockcanopies.Here,itisobviousthatsalt-stocksarecoalescingtoformasalt-stockcanopy.

盐接合线

AllochthonoussaltsheetsorsSecondarysaltweldshaveoftenaverticalgeometry,orundatedwhenlateregionalcompressionstakeplace.Aprimaryandatertiarysaltweldsarealsoeasilyrecognized.再生的盐连接4.复杂成因盐构造SecondarysaltweldshaveofteFig.16-IntheCaspianSea,nearbythehugeKasaghanoildiscovery(darkblue),saltridgesstrikeperpendicularlytothethrust-faultsandcylindrical-foldsofthefold-belt(intheleftendoftheline).Therefore,isquitepossiblethantheywerecreatedbythelesseningtectonicregime(seetablesIandII).张扭性盐构造Fig.16-IntheCaspianSea,nFig.19-Thisantiformstructureisatypicalextensionalstructurecreatedbyhalokinesis.Thelateraldepocentersisasynkinematicintervalsdepositedinassociationwithacompensatorysubsidencecreatedbysaltflowage.Thecoreofthestructure,whichismainlyprekinematic,wasinvertedbyhalokinesis.Thenormal-faults(withoppositevergence)neartheapexofthestructurestronglyextendtheoverburden.盐构造作用Fig.19-ThisantiformstructuTectonicinversions,astheoneillustratedonthisseismicline,implylengtheningoftheuppersedimentarylayers.Therefore,normalfaultingisalwaysassociatedwith.Thepresenceorabsenceofnormalfaults,neartheapexofdomalstructures,canbeusedtodifferentiateinversionsfromanticlines.构造反转Tectonicinversions,astheonInoffshoreAngola,aswellasinonshore,thesaltsourcelayeristheAptiansaltwhich,stratigraphicallyspeaking,itwasdepositedabovetheCretaceousbasalsandstones(yellow,CuvoandChelaformation)ofthedivergentmarginandbelowtheAlbianlimestones(green,BingaandPindaformations).InAngola-GabonandBrazil,thesourcelayersaredifferent.Indeed,andcontrariwisetoanerroneoushypothesis,stillfollowedbysomegeologists,theseAptiansaltbasinswerealwaysindividualizedbysubaerialandoceanicspreadingcenter.InoffshoreAngola,aswellasOnthisseismic,wherethe

autochthonousandallochthonoussaltlayersareeasilyrecognize,secondorderdiapirsareindividualized.Onthisseismic,wheretheautShearzonesandparticularlyfaultzonesareoftenfeedersofsaltextrusionasillustratedonthisseismicline.Actually,onthisarea,someofthesefault,smoreorlessinjectedbysalt,areseismicallyactivesandhavebeenthesourceofmajorearthquakes.ShearzonesandparticularlyfIntheGulfCoast,asillustratedabove,themajorityoftheallochthonoussaltstructurehavebeeninflatedmainlyduetodifferentialloading.

席状或舌状增厚IntheGulfCoast,asillustraFig.21-Halokinesiscancreatecomplexstructuresparticularlywhenthereissuperimpositionofautochthonousandallochthonoussaltstructures,asisthecaseonthisseismiclinefromGardenBanks(deep-waterGulfofMexico),where,atleasttwosalt-inducedtectonicdisharmoniesordécollementsurfacescanpredicted.盐构造作用外来盐Fig.21-HalokinesiscancreatOnthisline,itisquiteevidentthattheallochthonoussalt

structurewascreatedbysaltinjectionunderrelativethinsedimentarycover(thinnerthanpresently).盐床注入Onthisline,itisquiteevidAsillustratedonthisseismicline,theoriginalsaltsheet

issplittingupbyaprogressivewestwarddevelopmentofsaltexpulsionbasins.Thecounter-regionalfaults,inthecentralpartoftheline,istheramp

orthefeederofthe

saltsheet.席状分裂AsillustratedonthisseismicThedepocenterabovethesaltdomecanbeexplainedasaconsequenceofasaltcollapsefollowingthesubsurfaceerosionduetosaltdissolution.潜蚀作用ThedepocenterabovethesaltOnthisseismicline,

sub-saltstrataiscomposedbythebasalCretaceoussandstoneofthemargin(inyellow)andrift-typebasinsediments(inbrown).Theinfrastructureofthesub-saltstrataisthePrecambrian

basement.Onthisseismicline,sub-saltGenerally,inacontinentaldivergentmargin,thesubstratumisformedbyinfra-saltmarginsediments,whichoverlyeitherarift-typebasinsediments,aPaleozoicfoldbeltoraPrecambrianbasement.Onthisparticularexample,inwhichtheinfra-saltmarginsedimentsareunderseismicresolution,thesubstratumofthesaltisaPrecambrianbasement.底部层Generally,inacontinentaldiSalt-tonguecanopiesarequitedifficulttorecognizeonseismiclines.However,theycaneasilytoberecognizedonshallowtimeslicesknowingtheabovegeologicalmodel.Indeed,seismicinterpreterscanonlyrecognizeonseismicdatawhattheyknown,i.e.,inseismicinterpretationTheoryprecedesObservation.三、盐构造空间特征舌状盐盖缝合线叶状生长边缘发育程度增加Salt-tonguecanopiesarequiteAsillustratedabove,withtime,saltwallscancoalescedandformquitelargesaltwallcanopies.Often,timeslicesallowtorecognizethesuturesbetweenthedifferentsaltwallsorthesuturesynforms,whichalloweasilydifferentiatesaltwallcanopiesfromsaltnapes.墙状盐盖缝合线缝合向斜缝合交接背斜发育程度增加Asillustratedabove,withtimSaltwallsareeasilyrecognisedontimeslicesorongeologicalmaps.Onthismap,thesaltstructures(inblack)aremainlyelongated,particularlyonthesouthernpart,andparalleltotheshoreline。SaltwallsareeasilyrecognisFig.15-Thissketchillustratestheconjecturethatthetectonicstressdecreaseprogressivelyindirectionofthecraton,thatistosay,awayfromtheorogenicbelt.Indeed,thetectonicstressismoreorlessconstantwithintheconsideredlithosphericplate.However,asthestrengthtodeformationoftherockschange,deformationoccurswherethesedimentscannotstandanymoretheeffectivestresses.Insuchatectonicsetting,when1

isvertical,saltlayers,iftheyweredepositedwillbedeformedinsaltridgesstrikingperpendicularlytothecylindrical-foldsandthrustsofthefold-belt.前陆造山带理想化的变形情况四、区域盐构造特征Fig.15-ThissketchillustratSomegeologistsusedtheSaltTectonicswhenanextensionaltectonicregime

isactive,and

Halokinesiswhens